See Lawrence Principe, The Secrets of Alchemy (2013, The University of Chicago Press), page 33-on for Jabir and the Jabirian Corpus:

"a person who played as large a role in Arabic alchemy as Zosimos did in the Greco-Egyptian—one Jabir ibn-Ḥayyan. Or, to speak more accurately, several Jabir ibn-Ḥayyans. Or perhaps none at all. A persistent problem facing historians of alchemy is figuring out if an author really is who he says he is, and if he lived when and where he claims"

And see page 55:

"the most influential of these 13th-century Latin alchemical compositions appeared under a very familiar name, that of Jabir, rendered in medieval Latin spelling as Geber. Thus, the “Jabir problem” discussed in the previous chapter had yet another dimension: whether the Latin books known under the name of Geber were translations of Jbir, or whether they were native Latin productions. Historians of science argued vociferously over whether Geber was really Jabir. Recent scholarship has settled the issue: he was not. Geber was a late thirteenth-century Latin author."

"The author concealed behind the pseudonym of Geber is probably an Italian Franciscan friar and lecturer named Paul of Taranto. [Footnote. We owe this identification, and the solution to the “Jabir-Geber” problem,to the painstaking studies of William R. Newman. For a detailed treatment of Geber’s identity, see Newman, “New Light on the Identity of Geber,” Sudhoffs Archiv 69 (1985): 79–90, and “Genesis of the Summa perfectionis,” Archives internationales d’histoire des sciences 35 (1985): 240–302. For an edition, translation, and historical contextualization of the Summa, see Newman’s The Summa Perfectionis of Pseudo-Geber.]"

See Lawrence Principe, The Secrets of Alchemy (2013, The University of Chicago Press), page 33-on for Jabir and the Jabirian Corpus:

"a person who played as large a role in Arabic alchemy as Zosimos did in the Greco-Egyptian—one Jabir ibn-Ḥayyan. Or, to speak more accurately, several Jabir ibn-Ḥayyans. Or perhaps none at all. A persistent problem facing historians of alchemy is figuring out if an author really is who he says he is, and if he lived when and where he claims."

And see page 55:

"the most influential of these 13th-century Latin alchemical compositions appeared under a very familiar name, that of Jabir, rendered in medieval Latin spelling as Geber. Thus, the “Jabir problem” discussed in the previous chapter had yet another dimension: whether the Latin books known under the name of Geber were translations of Jbir, or whether they were native Latin productions. Historians of science argued vociferously over whether Geber was really Jabir. Recent scholarship has settled the issue: he was not. Geber was a late thirteenth-century Latin author."

"The author concealed behind the pseudonym of Geber is probably an Italian Franciscan friar and lecturer named Paul of Taranto. [Footnote. We owe this identification, and the solution to the “Jabir-Geber” problem,to the painstaking studies of William R. Newman. For a detailed treatment of Geber’s identity, see Newman, “New Light on the Identity of Geber,” Sudhoffs Archiv 69 (1985): 79–90, and “Genesis of the Summa perfectionis,” Archives internationales d’histoire des sciences 35 (1985): 240–302. For an edition, translation, and historical contextualization of the Summa, see Newman’s The Summa Perfectionis of Pseudo-Geber.]"